/*
 *  linux/kernel/sys.c
 *
 *  (C) 1991  Linus Torvalds
 */



#include "../include/errno.h"
#include "../include/linux/sched.h"
#include "../include/asm/segment.h"
#include "../include/sys/utsname.h"
#include "../include/linux/config.h"
#include "../include/string.h"
#include "../include/sys/times.h"

/*
 * The timezone where the local system is located.  Used as a default by some
 * programs who obtain this value by using gettimeofday.
 */
struct timezone sys_tz = { 0, 0};

extern int session_of_pgrp(int pgrp);

int sys_ftime()
{
    return -ENOSYS;
}

int sys_break()
{
    return -ENOSYS;
}

int sys_ptrace()
{
    return -ENOSYS;
}

int sys_stty()
{
    return -ENOSYS;
}

int sys_gtty()
{
    return -ENOSYS;
}

int sys_rename()
{
    return -ENOSYS;
}

int sys_prof()
{
    return -ENOSYS;
}

/*
 * This is done BSD-style, with no consideration of the saved gid, except
 * that if you set the effective gid, it sets the saved gid too.  This
 * makes it possible for a setgid program to completely drop its privileges,
 * which is often a useful assertion to make when you are doing a security
 * audit over a program.
 *
 * The general idea is that a program which uses just setregid() will be
 * 100% compatible with BSD.  A program which uses just setgid() will be
 * 100% compatible with POSIX w/ Saved ID's.
 */
int sys_setregid(int rgid, int egid)
{
    if (rgid>0) {
        if ((current->gid == rgid) ||
            suser())
            current->gid = rgid;
        else
            return(-EPERM);
    }
    if (egid>0) {
        if ((current->gid == egid) ||
            (current->egid == egid) ||
            suser()) {
            current->egid = egid;
            current->sgid = egid;
        } else
            return(-EPERM);
    }
    return 0;
}

/*
 * setgid() is implemeneted like SysV w/ SAVED_IDS
 */
int sys_setgid(int gid)
{
    if (suser())
        current->gid = current->egid = current->sgid = gid;
    else if ((gid == current->gid) || (gid == current->sgid))
        current->egid = gid;
    else
        return -EPERM;
    return 0;
}

int sys_acct()
{
    return -ENOSYS;
}

int sys_phys()
{
    return -ENOSYS;
}

int sys_lock()
{
    return -ENOSYS;
}

int sys_mpx()
{
    return -ENOSYS;
}

int sys_ulimit()
{
    return -ENOSYS;
}

int sys_time(long * tloc)
{
    int i;

    i = CURRENT_TIME;
    if (tloc) {
        verify_area(tloc,4);
        put_fs_long(i,(unsigned long *)tloc);
    }
    return i;
}

/*
 * Unprivileged users may change the real user id to the effective uid
 * or vice versa.  (BSD-style)
 *
 * When you set the effective uid, it sets the saved uid too.  This
 * makes it possible for a setuid program to completely drop its privileges,
 * which is often a useful assertion to make when you are doing a security
 * audit over a program.
 *
 * The general idea is that a program which uses just setreuid() will be
 * 100% compatible with BSD.  A program which uses just setuid() will be
 * 100% compatible with POSIX w/ Saved ID's.
 */
int sys_setreuid(int ruid, int euid)
{
    int old_ruid = current->uid;

    if (ruid>0) {
        if ((current->euid==ruid) ||
            (old_ruid == ruid) ||
            suser())
            current->uid = ruid;
        else
            return(-EPERM);
    }
    if (euid>0) {
        if ((old_ruid == euid) ||
            (current->euid == euid) ||
            suser()) {
            current->euid = euid;
            current->suid = euid;
        } else {
            current->uid = old_ruid;
            return(-EPERM);
        }
    }
    return 0;
}

/*
 * setuid() is implemeneted like SysV w/ SAVED_IDS
 *
 * Note that SAVED_ID's is deficient in that a setuid root program
 * like sendmail, for example, cannot set its uid to be a normal
 * user and then switch back, because if you're root, setuid() sets
 * the saved uid too.  If you don't like this, blame the bright people
 * in the POSIX commmittee and/or USG.  Note that the BSD-style setreuid()
 * will allow a root program to temporarily drop privileges and be able to
 * regain them by swapping the real and effective uid.
 */
int sys_setuid(int uid)
{
    if (suser())
        current->uid = current->euid = current->suid = uid;
    else if ((uid == current->uid) || (uid == current->suid))
        current->euid = uid;
    else
        return -EPERM;
    return(0);
}

int sys_stime(long * tptr)
{
    if (!suser())
        return -EPERM;
    startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
    jiffies_offset = 0;
    return 0;
}

int sys_times(struct tms * tbuf)
{
    if (tbuf) {
        verify_area(tbuf,sizeof *tbuf);
        put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
        put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
        put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
        put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
    }
    return jiffies;
}

int sys_brk(unsigned long end_data_seg)
{
    if (end_data_seg >= current->end_code &&
        end_data_seg < current->start_stack - 16384)
        current->brk = end_data_seg;
    return current->brk;
}

/*
 * This needs some heave checking ...
 * I just haven't get the stomach for it. I also don't fully
 * understand sessions/pgrp etc. Let somebody who does explain it.
 *
 * OK, I think I have the protection semantics right.... this is really
 * only important on a multi-user system anyway, to make sure one user
 * can't send a signal to a process owned by another.  -TYT, 12/12/91
 */
int sys_setpgid(int pid, int pgid)
{
    int i;

    if (!pid)
        pid = current->pid;
    if (!pgid)
        pgid = current->pid;
    if (pgid < 0)
        return -EINVAL;
    for (i=0 ; i<NR_TASKS ; i++)
        if (task[i] && (task[i]->pid == pid) &&
            ((task[i]->p_pptr == current) ||
             (task[i] == current))) {
            if (task[i]->leader)
                return -EPERM;
            if ((task[i]->session != current->session) ||
                ((pgid != pid) &&
                 (session_of_pgrp(pgid) != current->session)))
                return -EPERM;
            task[i]->pgrp = pgid;
            return 0;
        }
    return -ESRCH;
}

int sys_getpgrp(void)
{
    return current->pgrp;
}

int sys_setsid(void)
{
    if (current->leader && !suser())
        return -EPERM;
    current->leader = 1;
    current->session = current->pgrp = current->pid;
    current->tty = -1;
    return current->pgrp;
}

/*
 * Supplementary group ID's
 */
int sys_getgroups(int gidsetsize, gid_t *grouplist)
{
    int	i;

    if (gidsetsize)
        verify_area(grouplist, sizeof(gid_t) * gidsetsize);

    for (i = 0; (i < NGROUPS) && (current->groups[i] != NOGROUP);
         i++, grouplist++) {
        if (gidsetsize) {
            if (i >= gidsetsize)
                return -EINVAL;
            put_fs_word(current->groups[i], (short *) grouplist);
        }
    }
    return(i);
}

int sys_setgroups(int gidsetsize, gid_t *grouplist)
{
    int	i;

    if (!suser())
        return -EPERM;
    if (gidsetsize > NGROUPS)
        return -EINVAL;
    for (i = 0; i < gidsetsize; i++, grouplist++) {
        current->groups[i] = get_fs_word((unsigned short *) grouplist);
    }
    if (i < NGROUPS)
        current->groups[i] = NOGROUP;
    return 0;
}

int in_group_p(gid_t grp)
{
    int	i;

    if (grp == current->egid)
        return 1;

    for (i = 0; i < NGROUPS; i++) {
        if (current->groups[i] == NOGROUP)
            break;
        if (current->groups[i] == grp)
            return 1;
    }
    return 0;
}

static struct utsname thisname = {
        UTS_SYSNAME, UTS_NODENAME, UTS_RELEASE, UTS_VERSION, UTS_MACHINE
};

int sys_uname(struct utsname * name)
{
    int i;

    if (!name) return -ERROR;
    verify_area(name,sizeof *name);
    for(i=0;i<sizeof *name;i++)
        put_fs_byte(((char *) &thisname)[i],i+(char *) name);
    return 0;
}

/*
 * Only sethostname; gethostname can be implemented by calling uname()
 */
int sys_sethostname(char *name, int len)
{
    int	i;

    if (!suser())
        return -EPERM;
    if (len > MAXHOSTNAMELEN)
        return -EINVAL;
    for (i=0; i < len; i++) {
        if ((thisname.nodename[i] = get_fs_byte(name+i)) == 0)
            break;
    }
    if (thisname.nodename[i]) {
        thisname.nodename[i>MAXHOSTNAMELEN ? MAXHOSTNAMELEN : i] = 0;
    }
    return 0;
}

int sys_getrlimit(int resource, struct rlimit *rlim)
{
    if (resource >= RLIM_NLIMITS)
        return -EINVAL;
    verify_area(rlim,sizeof *rlim);
    put_fs_long(current->rlim[resource].rlim_cur,
                (unsigned long *) rlim);
    put_fs_long(current->rlim[resource].rlim_max,
                ((unsigned long *) rlim)+1);
    return 0;
}

int sys_setrlimit(int resource, struct rlimit *rlim)
{
    struct rlimit new, *old;

    if (resource >= RLIM_NLIMITS)
        return -EINVAL;
    old = current->rlim + resource;
    new.rlim_cur = get_fs_long((unsigned long *) rlim);
    new.rlim_max = get_fs_long(((unsigned long *) rlim)+1);
    if (((new.rlim_cur > old->rlim_max) ||
         (new.rlim_max > old->rlim_max)) &&
        !suser())
        return -EPERM;
    *old = new;
    return 0;
}

/*
 * It would make sense to put struct rusuage in the task_struct,
 * except that would make the task_struct be *really big*.  After
 * task_struct gets moved into malloc'ed memory, it would
 * make sense to do this.  It will make moving the rest of the information
 * a lot simpler!  (Which we're not doing right now because we're not
 * measuring them yet).
 */
int sys_getrusage(int who, struct rusage *ru)
{
    struct rusage r;
    unsigned long	*lp, *lpend, *dest;

    if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
        return -EINVAL;
    verify_area(ru, sizeof *ru);
    memset((char *) &r, 0, sizeof(r));
    if (who == RUSAGE_SELF) {
        r.ru_utime.tv_sec = CT_TO_SECS(current->utime);
        r.ru_utime.tv_usec = CT_TO_USECS(current->utime);
        r.ru_stime.tv_sec = CT_TO_SECS(current->stime);
        r.ru_stime.tv_usec = CT_TO_USECS(current->stime);
    } else {
        r.ru_utime.tv_sec = CT_TO_SECS(current->cutime);
        r.ru_utime.tv_usec = CT_TO_USECS(current->cutime);
        r.ru_stime.tv_sec = CT_TO_SECS(current->cstime);
        r.ru_stime.tv_usec = CT_TO_USECS(current->cstime);
    }
    lp = (unsigned long *) &r;
    lpend = (unsigned long *) (&r+1);
    dest = (unsigned long *) ru;
    for (; lp < lpend; lp++, dest++)
        put_fs_long(*lp, dest);
    return(0);
}

int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
{
    if (tv) {
        verify_area(tv, sizeof *tv);
        put_fs_long(startup_time + CT_TO_SECS(jiffies+jiffies_offset),
                    (unsigned long *) tv);
        put_fs_long(CT_TO_USECS(jiffies+jiffies_offset),
                    ((unsigned long *) tv)+1);
    }
    if (tz) {
        verify_area(tz, sizeof *tz);
        put_fs_long(sys_tz.tz_minuteswest, (unsigned long *) tz);
        put_fs_long(sys_tz.tz_dsttime, ((unsigned long *) tz)+1);
    }
    return 0;
}

/*
 * The first time we set the timezone, we will warp the clock so that
 * it is ticking GMT time instead of local time.  Presumably,
 * if someone is setting the timezone then we are running in an
 * environment where the programs understand about timezones.
 * This should be done at boot time in the /etc/rc script, as
 * soon as possible, so that the clock can be set right.  Otherwise,
 * various programs will get confused when the clock gets warped.
 */
int sys_settimeofday(struct timeval *tv, struct timezone *tz)
{
    static int	firsttime = 1;
    void 		adjust_clock();

    if (!suser())
        return -EPERM;
    if (tz) {
        sys_tz.tz_minuteswest = get_fs_long((unsigned long *) tz);
        sys_tz.tz_dsttime = get_fs_long(((unsigned long *) tz)+1);
        if (firsttime) {
            firsttime = 0;
            if (!tv)
                adjust_clock();
        }
    }
    if (tv) {
        int sec, usec;

        sec = get_fs_long((unsigned long *)tv);
        usec = get_fs_long(((unsigned long *)tv)+1);

        startup_time = sec - jiffies/HZ;
        jiffies_offset = usec * HZ / 1000000 - jiffies%HZ;
    }
    return 0;
}

/*
 * Adjust the time obtained from the CMOS to be GMT time instead of
 * local time.
 *
 * This is ugly, but preferable to the alternatives.  Otherwise we
 * would either need to write a program to do it in /etc/rc (and risk
 * confusion if the program gets run more than once; it would also be
 * hard to make the program warp the clock precisely n hours)  or
 * compile in the timezone information into the kernel.  Bad, bad....
 *
 * XXX Currently does not adjust for daylight savings time.  May not
 * need to do anything, depending on how smart (dumb?) the BIOS
 * is.  Blast it all.... the best thing to do not depend on the CMOS
 * clock at all, but get the time via NTP or timed if you're on a
 * network....				- TYT, 1/1/92
 */
void adjust_clock()
{
    startup_time += sys_tz.tz_minuteswest*60;
}

int sys_umask(int mask)
{
    int old = current->umask;

    current->umask = mask & 0777;
    return (old);
}
